Heat pump hot water apparatus

ABSTRACT

According to a heat pump hot water apparatus of the invention, the hot water tank  7  is disposed on one side of the casing  50 , the antifreeze liquid circulating means  41  and the heat pump circuit are disposed on the other side of the casing  50 , and the water/refrigerant heat exchanger  2  is disposed at a location higher than the compressor  1 . According to this configuration, the heat pump circuit and the hot water tank circuit are accommodated in one casing  50 , stability and noise-reduction effect can be realized when the heat pump hot water apparatus is installed, and the casing  50  can be made smaller in size by enhancing layout balance of functional parts in the casing  50.

TECHNICAL FIELD

The present invention relates to a heat pump hot water apparatus whichheats a room with hot water produces by using a heat pump circuit whichutilizes earth thermal.

BACKGROUND TECHNIQUE

Most of conventional heaters use fuel of a combustion system such aspetroleum and gas as a heat source but in recent years, heating marketusing a heat pump technique is rapidly growing. Conventional airconditioners can also both cool and heat a room utilizing the heat pumptechnique.

However, the conventional air conditioner has a problem that it isdifficult to warm feet at the time of a heating operation and to solvethis problem, hot water apparatuses utilizing the heat pump techniquehave been developed (patent document 1).

According to the hot water apparatus described in patent document 1,heat is exchanged between high temperature refrigerant and hot water,and hot water which is heated by the heat exchange is sent to a heatingterminal such as a floor heating panel, thereby heating a room.

A heat pump hot water supply apparatus in which utilizes earth thermalhas been already proposed (patent document 2).

PRIOR ART DOCUMENTS Patent Document

-   [Patent Document 1] Japanese Patent Application Laid-open No.    2008-39305-   [Patent Document 2] Japanese Patent Application Laid-open No.    2007-64540

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

According to the heat pump hot water apparatus of the patent document 1,a hot water supply heat exchanger is vertically provided in a hot watertank, and since hot water for hot water supply is produced using hotwater which is to be sent to a heating terminal, a temperature of theentire hot water in the hot water tank is decreased. As a result, atemperature of hot water to be sent to the heating terminal is decreasedand comfort at the heating terminal is deteriorated.

A heat pump water heater which utilizes earth thermal is generallyinstalled indoors in Europe and the like, and if a depth dimension ofthe water heater as a product is 600 mm or less, installationperformance is excellent. According to patent document 2, however, awater heater body unit in which a heat pump cycle is accommodated and atank unit in which a hot water tank is accommodated are separate units,and patent document 2 has a problem that an installation area isincreased.

The present invention has been accomplished to solve the conventionalproblem, and it is an object of the invention to provide a heat pump hotwater apparatus in which a heat pump circuit and a hot water tankcircuit are accommodated in one casing and which stability andnoise-reduction effect can be realized when the heat pump hot waterapparatus is installed, and the casing can be made smaller in size byenhancing layout balance of functional parts in the casing.

Means for Solving the Problem

To solve the conventional problem, according to a heat pump hot waterapparatus of the invention, the hot water tank is disposed on one ofsides of the casing, the antifreeze liquid circulating means and theheat pump circuit are disposed on the other side of the casing, and thewater/refrigerant heat exchanger is disposed at a location higher thanthe compressor. According to the invention, a heavy compressor whichlargely vibrates is disposed on a bottom plate, and a water/refrigerantheat exchanger is disposed above the compressor. According to thisconfiguration, stability and noise-reduction effect can be realized whenthe heat pump hot water apparatus is installed, and the casing can bemade smaller in size by enhancing layout balance of functional parts inthe casing.

Effect of the Invention

According to the invention, the heat pump circuit and the hot water tankcircuit can be accommodated in one casing. According to thisconfiguration, stability and noise-reduction effect can be realized whenthe heat pump hot water apparatus is installed, and the casing can bemade smaller in size by enhancing layout balance of functional parts inthe casing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a heat pump hot water apparatus accordingto an embodiment of the present invention; and

FIG. 2 is a diagram showing a schematic configuration of an essentialportion of an interior of the heater as viewed from a front surface of acasing of the embodiment.

EXPLANATION OF SYMBOLS

-   1 compressor-   2 water/refrigerant heat exchanger-   3 decompressor-   4 antifreeze liquid refrigerant heat exchanger-   5 four-way valve-   6 refrigerant pipe-   7 hot water tank-   8 partition plate-   9 water circulating means-   10 water outlet-   11 hot water port-   12 a, 12 b temperature sensor-   13 flow switch-   14 over pressure relief valve-   15 a upper heater-   15 b lower heater-   16 a, 16 b, 16 c, 16 d temperature sensor-   17 hot water supply terminal-   18 hot water supply heat exchanger-   19 hot water supply pump-   20 hot water-outflow port-   21 water-inflow port-   22 flow rate adjusting valve-   23 check valve-   24 over pressure relief valve-   25 waste plug-   26 water supply pipe-   27 three-way valve-   28 over pressure relief valve-   29 over pressure relief valve-   30 hot water supply pipe-   31 temperature sensor-   32 auxiliary temperature sensor-   33 flow rate sensor-   34 heating terminal-   35 heating pump-   36 hot water take-out port-   37 first expansion tank-   41 antifreeze liquid circulating means-   42 earth thermal heat exchanger-   44 second expansion tank-   50 casing

MODE FOR CARRYING OUT THE INVENTION

According to a heat pump hot water apparatus of a first aspect of theinvention, the hot water tank is disposed on one of sides of the casing,the antifreeze liquid circulating means and the heat pump circuit aredisposed on the other side of the casing, and the water/refrigerant heatexchanger is disposed at a location higher than the compressor.According to this aspect, a heavy compressor which largely vibrates isdisposed on a bottom plate, and a water/refrigerant heat exchanger isdisposed above the compressor. According to this configuration,stability and noise-reduction effect can be realized when the heat pumphot water apparatus is installed, and the casing can be made smaller insize by enhancing layout balance of functional parts in the casing.

According to a second aspect of the invention, in the heat pump hotwater apparatus of the first aspect, the water/refrigerant heatexchanger and the antifreeze liquid refrigerant heat exchanger aredisposed at locations higher than the compressor and the antifreezeliquid circulating means. According to this aspect, a heavy compressorand an antifreeze liquid circulating means which largely vibrate aredisposed on a bottom plate, and a water/refrigerant heat exchanger andan antifreeze liquid refrigerant heat exchanger are disposed above thecompressor and the antifreeze liquid circulating means. According tothis configuration, stability and noise-reduction effect can be realizedwhen a product is installed, and a body can be made smaller in size byenhancing layout balance of functional parts in the casing.

According to a third aspect of the invention, in the heat pump hot waterapparatus of the first or second aspect, the first expansion tank isdisposed at a location higher than the hot water tank. According to thisaspect, it is possible to increase an adaptable water amount in a firstexpansion tank with respect to an amount of water in a boiling circuitwhich circulates through a water/refrigerant heat exchanger and a hotwater tank.

According to a fourth aspect of the invention, in the heat pump hotwater apparatus of the third aspect, a hermetic second expansion tankconnected to the antifreeze liquid circuit, wherein the second expansiontank is disposed at a location higher than the antifreeze liquidrefrigerant heat exchanger. According to this aspect, it is possible toincrease an adaptable antifreeze liquid amount in a second expansiontank with respect to an antifreeze liquid amount in an antifreeze liquidcircuit.

According to a fifth aspect of the invention, in the heat pump hot waterapparatus of the fourth aspect, the first expansion tank is disposed onthe one side of the casing, and the second expansion tank is disposed onthe other side of the casing. According to this aspect, the body can bemade smaller in size by enhancing layout balance of functional parts inthe casing.

Embodiments of the present invention will be explained below withreference to the drawings. The invention is not limited to theembodiments.

First, a configuration a heat pump hot water apparatus of the embodimentwill be explained. FIG. 1 is a block diagram of the heat pump hot waterapparatus of the embodiment of the invention. The heat pump hot waterapparatus of the embodiment includes a heat pump circuit, a hot watertank circuit and an antifreeze liquid circuit. The heat pump circuit, aboiling circuit in the hot water tank circuit and an antifreeze liquidcirculating means (pump) 41 which configures an antifreeze liquidcircuit are accommodated in one casing 50, and the casing 50 is disposedout of doors.

The heat pump circuit includes a compressor 1 which compresses anddischarge a e refrigerant, a water/refrigerant heat exchanger 2 whichabsorbs heat from the refrigerant discharged from the compressor 1 toproduce hot water, a decompressor 3 which decompresses a refrigerantwhich dissipates heat in the water/refrigerant heat exchanger 2, anantifreeze liquid refrigerant heat exchanger 4 which absorbs heat fromthe antifreeze liquid by the refrigerant decompressed by thedecompressor 3, and a four-way valve 5 which changes flow paths of arefrigerant. The compressor 1, the water/refrigerant heat exchanger 2,the decompressor 3, the antifreeze liquid refrigerant heat exchanger 4and the four-way valve 5 are annularly connected to one another througha refrigerant pipe 6, thereby forming a heat pump circuit. As thewater/refrigerant heat exchanger 2 and the antifreeze liquid refrigerantheat exchanger 4, a high efficient plate type heat exchanger is used. Inthe heat pump circuit, R410A is used as a refrigerant, butchlorofluorocarbons-based refrigerant of R407C is more suitable.

An antifreeze liquid circuit includes antifreeze liquid circulatingmeans 41 which makes antifreeze liquid circulate, and an earth thermalheat exchanger 42 which absorbs earth thermal by the antifreeze liquid.A hermetic second expansion tank 44 is connected to the antifreezeliquid circuit. An interior of the second expansion tank 44 is dividedby a diaphragm into an antifreeze liquid chamber and an air chamber, andcapacities of the antifreeze liquid chamber and the air chamber arechanged by the diaphragm. Therefore, the second expansion tank 44 canabsorb expansion of the antifreeze liquid in the antifreeze liquidcircuit. It is preferable that the second expansion tank 44 is connectedto an upper portion of an antifreeze liquid refrigerant heat exchanger4.

The hot water tank circuit includes a hot water tank 7 in which hot/coldwater is stored. A partition plate 8 is disposed in the hot water tank 7at a substantially intermediate portion thereof in a height direction ofthe hot water tank 7. In the hot water tank 7, an upper space which ishigher than the partition plate 8 is a hot water supply-hot watersection 7 a, and a lower space which is lower than the partition plate 8is a heating hot water section 7 b. By partitioning the interior of thehot water tank 7 into the upper space and the lower space, hot water inthe hot water supply-hot water section 7 a can be used for heat exchangewhen hot water is supplied, and hot water in the heating hot watersection 7 b can be used for circulating to the heating terminal when aroom is heated.

A water outlet 10 is provided in a lower portion of the hot water tank7. A water pipe through which low temperature water is sent from thewater outlet 10 to the water/refrigerant heat exchanger 2 is providedwith water circulating means (pump) 9. By driving the water circulatingmeans 9, low temperature water is sent from the water outlet 10 to thewater/refrigerant heat exchanger 2, the water/refrigerant heat exchanger2 absorbs heat from the refrigerant and hot water is produced.

Hot water produced by the water/refrigerant heat exchanger 2 is returnedto a hot water inlet 11 provided in an upper portion of the heating hotwater section 7 b. In this embodiment, the hot water tank 7, the wateroutlet 10, the water circulating means 9, the water/refrigerant heatexchanger 2 and the hot water inlet 11 are connected to one anotherthrough a water pipe, thereby forming a boiling circuit. An AC pumphaving a constant circulation flow rate is used as the water circulatingmeans 9.

The partition plate 8 has a plurality of openings, when hot water heatedby the heat pump circuit returns to the heating hot water section 7 b,the hot water flows into the hot water supply-hot water section 7 athrough the openings.

A periphery of the partition plate 8 and an inner wall of the hot watertank 7 are welded to each other through a plurality of welding points,and gaps are provided between the periphery of the partition plate 8 andthe hot water tank 7 other than the welding points. Hot water whichreturned from the hot water inlet 11 flows into the hot water supply-hotwater section 7 a through the gaps formed between the periphery of thepartition plate 8 and the hot water tank 7.

Stainless steel is used for the hot water tank 7 and the partition plate8 in view of corrosion resistance.

A temperature sensor 12 a which detects an inflow-water temperature isprovided at a water-side inlet of the water/refrigerant heat exchanger2, and a temperature sensor 12 b which detects an outflow-watertemperature is provided at a water-side outlet of the water/refrigerantheat exchanger 2. A flow switch 13 is provided for detecting thathot/cold water flows through the boiling circuit.

The water circulating means 9, the flow switch 13 and an over pressurerelief valve 14 are provided in upstream and downstream pipes of thewater/refrigerant heat exchanger 2. The flow switch 13 detects flow ofhot/cold water. The flow switch 13 is disposed downstream of the watercirculating means 9. Since the flow switch 13 is disposed downstream ofthe water circulating means 9, it is possible to detect that the watercirculating means 9 is not normally operated.

The over pressure relief valve 14 which adjusts a pressure in theboiling circuit is provided above the water circulating means 9. If anabnormal condition is encountered in the boiling circuit and an internalpressure rises and becomes higher than a set pressure of the overpressure relief valve 14, expanded hot/cold water can be discharged fromthe over pressure relief valve 14.

An upper heater 15 a is disposed in the hot water supply-hot watersection 7 a, and a lower heater 15 b is disposed in the heating hotwater section 7 b. The upper heater 15 a is used for heating hot waterin the hot water supply-hot water section 7 a, and the lower heater 15 bis used for heating hot water in the heating hot water section 7 b.

Temperature sensors 16 a, 16 b, 16 c and 16 d are disposed on a sidewall of the hot water tank 7 for detecting a temperature of hot/coldwater in the hot water tank 7. The temperature sensor 16 a is disposedabove the upper heater 15 a, and the temperature sensor 16 b is disposedat substantially the same height as the upper heater 15 a. Thetemperature sensor 16 c is disposed at a location lower than thepartition plate 8 and higher than the lower heater 15 b, and thetemperature sensor 16 d is disposed at substantially the same height asthe lower heater 15 b.

The hot water tank circuit is provided with a hot water supply heatexchanger 18 which produces hot water to be sent to a hot water supplyterminal 17. High temperature water in the hot water tank 7 is sent to aprimary-side flow path of the hot water supply heat exchanger 18, andlow temperature water is sent from a water supply source to asecondary-side flow path of the hot water supply heat exchanger 18.

A hot water supply pump 19 is provided in a water pipe through whichhigh temperature water in the hot water tank 7 is sent to the hot watersupply heat exchanger 18. A hot water-outflow port 20 is provided in anupper portion of the hot water supply-hot water section 7 a of the hotwater tank 7, and a water-inflow port 21 is provided in a lower portionof the heating hot water section 7 b of the hot water tank 7. By drivingthe hot water supply pump 19, high temperature water is sent from thehot water-outflow port 20 to a primary-side flow path of the hot watersupply heat exchanger 18.

Hot water after heat is exchanged by the hot water supply heat exchanger18 is returned from the water-inflow port 21 into the hot water tank 7.In this embodiment, the hot water tank 7, the hot water-outflow port 20,the hot water supply heat exchanger 18, the hot water supply pump 19 andthe water-inflow port 21 are connected to one another through the waterpipe to form a hot water supply circuit. An AC pump whose circulationflow rate is constant is used as the hot water supply pump 19.

A water pipe between the hot water supply pump 19 and the water-inflowport 21 is provided with a check valve 23 and a flow rate adjustingvalve 22 which adjusts a circulation flow rate of hot/cold water in theboiling circuit. The check valve 23 is provided to prevent convection ofhot/cold water in the hot water supply circuit. This is because when thehot water supply pump 19 is not driven, the check valve 23 prevents hightemperature water in an upper portion of the hot water tank 7 fromentering a lower portion of the hot water tank 7 through the hot watersupply heat exchanger 18. If the high temperature water flows into thelower portion of the hot water tank 7, a temperature of hot water whichis sent to the water/refrigerant heat exchanger 2 becomes high andboiling efficiency is deteriorated.

In this embodiment, by providing the check valve 23, only when a flowrate becomes equal to a predetermined load or higher, hot/cold water iscirculated through the hot water supply circuit in a normal direction.In the embodiment, only when a load of 20 g is applied in the normaldirection of the check valve 23, hot/cold water flows in the normaldirection. The value of the load is not limited to 20 g.

An over pressure relief valve 24 which adjusts a pressure in the hotwater supply circuit is provided in a water pipe extending from the hotwater-outflow port 20 to the hot water supply heat exchanger 18. If thepressure in the hot water supply circuit becomes higher than a setpressure of the over pressure relief valve 24, hot/cold water isdischarged from the over pressure relief valve 24. The hot water tank 7is provided at its lower portion with a water plug 25, and hot/coldwater in the hot water tank 7 can be discharged outside.

A water line extending from the water supply source is connected to awater supply pipe 26 through an intake connection port 51. The watersupply pipe 26 is connected to a bottom of the hot water tank 7 and asecondary-side flow path of the hot water supply heat exchanger 18through a three-way valve 27.

When the hot water tank circuit is installed, the three-way valve 27 isswitched to a flow path which is connected to the hot water tank 7, thetank 7 is filled with water, and after the hot water tank 7 becomes fullof water, the three-way valve 27 is switched to a flow path which isconnected to the hot water supply heat exchanger 18. After water issupplied to the hot water tank 7, if the three-way valve 27 is switchedto the flow path connected to the hot water supply heat exchanger 18 inthis manner, a water circuit including the hot water tank 7 is closed,new water does not enter, and even if a user is living in an area ofhard water having a high mineral content, scale is deposited only fromwater which is put into the hot water tank 7 for the first time.

A water pipe between the three-way valve 27 and the hot water supplyheat exchanger 18 is provided with an over pressure relief valve 29. Awater supply pressure is applied from the water supply source directlyto the hot water supply heat exchanger 18. Hence, when the water supplypressure is high, if water is supplied from the water supply sourcedirectly to the hot water supply heat exchanger 18, there is apossibility that the hot water supply heat exchanger 18 is destroyed andbreaks down. Hence, the over pressure relief valve 29 is provided andwhen hot/cold water of more than given water supply pressure enters,water is discharged outside through the over pressure relief valve 29 toprevent the hot water supply heat exchanger 18 from breaking down.

If a temperature of low temperature water supplied from the water supplysource rises in the hot water supply heat exchanger 18, the lowtemperature water is supplied to the hot water supply terminal 17through a hot water supply pipe 30. The hot water supply terminal 17 isconnected to the hot water supply pipe 30 through a take-out connectionport 52. The hot water supply pipe 30 includes a temperature sensor 31and an auxiliary temperature sensor 32 which are hot water supplytemperature detecting means for detecting a temperature of hot/coldwater. The hot water supply pipe 30 also includes flow rate sensor 33which is flow rate detecting means for detecting a flow rate.

The heat pump hot water apparatus includes a heating terminal 34 forheating a room and it is possible to heat the room by circulating hotwater in the hot water tank 7 through the heating terminal 34. Theheating terminal 34 is connected to the hot water tank 7 through a hotwater outflow port 53 and a hot water inflow port 54. The heating pump35 sends hot water from the heating hot water section 7 b of the hotwater tank 7 to the heating terminal 34 through the hot water outflowport 53, and the hot water is returned from the heating terminal 34 tothe heating hot water section 7 b of the hot water tank 7 through thehot water inflow port 54. Hot water sent to the heating terminal 34 istaken out from a hot water take-out port 36 provided in the vicinity ofthe hot water inlet 11, and hot water in the heating hot water section 7b is supplied to the heating terminal 34. Hot water after it isheat-exchanged in the heating terminal 34 is returned to the bottom ofthe hot water tank 7. An AC pump having a constant circulation flow rateis used as the heating pump 35.

A hermetic first expansion tank 37 is connected to the hot water tank 7.An interior of the first expansion tank 37 is separated into a waterchamber and an air chamber by a diaphragm, and capacities of the waterchamber and the air chamber are changed by the diaphragm. Therefore, thefirst expansion tank 37 can absorb expansion of water in the circulationpath which configures the hot water tank circuit. The first expansiontank 37 may be connected to a pipe extending from the heating pump 35 tothe hot water outflow port 53 or a pipe extending from the hot waterinflow port 54 to the hot water tank 7, but it is preferable that thefirst expansion tank 37 is connected to an upper portion of the hotwater tank 7.

An operation of the heat pump hot water apparatus will be explainedbelow.

First, a boiling operation will be explained. First, a boilingtemperature Th of hot/cold water in the water/refrigerant heat exchanger2 is set. If the boiling operation is started, the water circulatingmeans 9 is driven and hot water in the hot water tank 7 is supplied tothe water/refrigerant heat exchanger 2. The boiling operation carriedout by the heat pump circuit is continued until a temperature detectedby the temperature sensor 12 b exceeds the boiling temperature Th. Whenhot water in the hot water tank 7 is to be boiled by the heat pumpcircuit, the four-way valve is switched such that high temperaturerefrigerant discharged from the compressor 1 flows into thewater/refrigerant heat exchanger 2.

As a result, high temperature refrigerant discharged from the compressor1 flows into the water/refrigerant heat exchanger 2, thereby dissipatingheat to hot/cold water and high temperature water can be produced. Inthe water/refrigerant heat exchanger 2, water and a refrigerant flow ina counter flowing manner so that the heat exchanging efficiency isenhanced.

If a temperature of hot/cold water coming from the water/refrigerantheat exchanger 2 detected by the temperature sensor 12 b approaches theboiling temperature Th, the revolution number of the compressor 1 isreduced to lower the ability. If the temperature detected by thetemperature sensor 12 b becomes higher than the boiling temperature Thby a predetermined temperature Ta (e.g., 2° C.), the operation of thecompressor 1 is stopped and the boiling operation is completed. The hotwater tank 7 is full of hot/cold water of the boiling temperature Th.

High temperature water produced by the water/refrigerant heat exchanger2 is returned to the heating hot water section 7 b, and the hot watersupply-hot water section 7 a is also full of hot/cold water of theboiling temperature Th through the gaps between the periphery of thepartition plate 8 and the hot water tank 7. At that time, aninflow-water temperature Ti detected by the temperature sensor 12 a whenthe operation of the compressor 1 is stopped is stored.

Also after the boiling operation carried out by the heat pump circuit iscompleted, the water circulating means 9 is driven and hot water in thehot water tank 7 is circulated through the water/refrigerant heatexchanger 2. This is because that it is necessary to detect atemperature of hot water in the hot water tank 7 by the temperaturesensor 12 a and the temperature sensor 12 b even while the boilingoperation is stopped, and the boiling operation carried out by the heatpump circuit must be restarted immediately when the temperature of heatexchanger in the hot water tank 7 is lowered.

The water circulating means 9 is driven even while the hot water supplyoperation is stopped, hot water in the hot water tank 7 is alwaysdetected by the temperature sensor 12 a, and when a temperature detectedby the temperature sensor 12 b becomes lower than the inflow-watertemperature Ti stored when the operation of the compressor 1 is stoppedby a predetermined temperature Tb (e.g., 5° C.), the operation of thecompressor 1 is restarted, and the boiling operation is started.

If the boiling temperature Tb is set to 55° C. for example, theoperation of the compressor 1 is stopped when a temperature detected bythe temperature sensor 12 b exceeds 57° C. (=55° C.+2° C.). If thetemperature detected by the temperature sensor 12 a when the operationof the compressor 1 is stopped is 53° C., the fact that the inflow-watertemperature Ti is 53° C. is stored. The water circulating means 9 isdriven even after the operation of the compressor 1 is stopped, and whena temperature detected by the temperature sensor 12 b becomes lower thanthe inflow-water temperature Ti only by a predetermined temperature Tb(e.g., 5° C.), the operation of the compressor 1 is restarted. Thepredetermined temperatures Ta and Tb shown in the embodiment are oneexample, and the invention is not limited to the embodiment.

In the hot water tank circuit, a boiling temperature Tu of the upperheater 15 a, a boiling temperature Tbo of the lower heater 15 b and ahot water supply temperature Tk to the hot water supply terminal 17 canbe set.

In the embodiment, by setting the boiling temperature Tu of the upperheater 15 a to a temperature higher than the boiling temperature Th, hotwater in the hot water supply-hot water section 7 a can be boiled to theboiling temperature Tu. If the boiling temperature Th is set to 55° C.and the boiling temperature Tu is set to 75° C. for example, the boilingoperation is carried out such that water is boiled to the boilingtemperature Th (55° C.) by the water/refrigerant heat exchanger 2 and itis boiled to 75° C. by the upper heater 15 a.

Since it is possible to set different boiling temperatures in the upperspace and the lower space between the partition plate 8, water can beboiled to an optimal temperature in accordance with respectiveterminals, and usability can be enhanced.

Next, a boiling operation carried out by the upper heater 15 a will beexplained. When the operation of the upper heater 15 a is to be started,output of the upper heater 15 a is turned ON when a temperature detectedby a temperature sensor 16 a provided at a location higher than theupper heater 15 a becomes lower than the boiling temperature Tu by apredetermined temperature Tc (e.g., 5° C.). Hot water in the hot watersupply-hot water section 7 a is heated by the upper heater 15 a, and theoutput of the upper heater 15 a is turned OFF when a temperaturedetected by a temperature sensor 16 b provided at the same location asthe upper heater 15 a becomes higher than the boiling temperature Tu bya predetermined temperature Td (e.g., 2° C.).

As described above, the temperature sensor 16 a which determines whenthe upper heater 15 a is turned ON and the temperature sensor 16 b whichdetermines when the upper heater 15 a is turned OFF are made differentfrom each other so that the upper heater 15 a is not frequently switchedbetween ON and OFF, and the durability of the upper heater 15 a isenhanced. The predetermined temperatures Tc and Td shown in theembodiment are one example, and the invention is not limited to theembodiment.

Next, a boiling operation carried out by the lower heater 15 b will beexplained. The lower heater 15 b is turned ON when the boiling operationcan not be carried out by a heat pump unit A, thereby preventing atemperature of hot water in the heating hot water section 7 b fromdecreasing.

If the heating operation is continued for example, frost forms on theantifreeze liquid refrigerant heat exchanger 4 and a defrostingoperation must be carried out. In such a case, a refrigerant flow pathis switched by the four-way valve 5, thereby flowing high temperaturerefrigerant coming from the compressor 1 into the antifreeze liquidrefrigerant heat exchanger 4, and the defrosting operation is carriedout at a temperature of the refrigerant.

However, when the defrosting operation is carried out, the refrigerantcan not dissipate heat by the water/refrigerant heat exchanger 2, hotwater can not be produced by the water/refrigerant heat exchanger 2. Asa result, a temperature of hot water in the heating hot water section 7b is decreased and this decreases a temperature of hot water to besupplied to the heating terminal 34. To prevent this, the lower heater15 b is turned ON, thereby preventing the temperature of hot water inthe heating hot water section 7 b from decreasing and comfort at theheating terminal 34 can be maintained. Not only during the defrostingoperation but also when the heat pump unit A breaks down, it is possibleto heat hot water in the heating hot water section 7 b by the lowerheater 15 b.

In this embodiment, control is performed such that only when atemperature detected by the temperature sensor 16 d is lower than aboiling temperature Tbo by the predetermined temperature Te (e.g., 10°C.), the lower heater 15 b is turned ON.

As a result, when the boiling temperature Tbo is set equal to theboiling temperature Th, water is boiled to the boiling temperature Th bythe heat pump circuit in the heating hot water section 7 b, and thelower heater 15 b is not turned ON unless a temperature detected by thetemperature sensor 16 d is lower than the boiling temperature Tbo by thepredetermined temperature Te.

When the defrosting operation of the antifreeze liquid refrigerant heatexchanger 4 is carried out or when ability of the heat pump circuit isnot exerted, the lower heater 15 b can be turned ON only when thetemperature detected by the temperature sensor 16 d is lower than theboiling temperature Tbo by the predetermined temperature Te, andextremely efficient boiling operation can be carried out.

When the boiling operation is carried out by the lower heater 15 b, ifthe lower heater 15 b is to be stopped, the boiling operation is carriedout such that the lower heater 15 b is turned ON when the temperaturedetected by the temperature sensor 16 d is higher than the boilingtemperature Tbo by a predetermined temperature Tf (e.g., 2° C.).

As described above, both the boiling operation carried out by the heatpump circuit and boiling operation carried out by the lower heater 15 bin combination are used in combination, even in a state where theboiling operation is not carried out by the heat pump unit A due todefrosting operation of the antifreeze liquid refrigerant heat exchanger4, hot water in the heating hot water section 7 b is maintained at theboiling temperature Tbo, the hot water can stably be sent to the heatingterminal 34, and comfort is not deteriorated. The predeterminedtemperatures Te and Tf shown in the embodiment are one example, and theinvention is not limited to the embodiment.

Next, a heating operation will be explained. If the heating operation isstarted, the heating pump 35 is driven and hot water in the heating hotwater section 7 b is supplied to the heating terminal 34. Hot waterwhich dissipated heat in the heating terminal 34 is returned to thelower portion in the hot water tank 7. At that time, since AC pump isused as the heating pump 35, hot/cold water of a given flow rate iscirculated at the time of the heating operation.

Next, a hot water supply operation will be explained. A hot water supplyset temperature Tk is set. If hot/cold water comes from the hot watersupply terminal 17 and the flow rate sensor 33 detects that a flow ratebecomes a predetermined flow rate or higher, the hot water supply pump19 is driven and high temperature water in the hot water supply-hotwater section 7 a is sent to the hot water supply heat exchanger 18.

An opening degree of the flow rate adjusting valve 22 is adjusted inaccordance with a temperature deviation between the temperature T1detected by the temperature sensor 31 and the hot water supply settemperature Tk, and feedback control is performed such that thetemperature T1 detected by the temperature sensor 31 becomes equal tothe hot water supply set temperature Tk. Hot water after it dissipatedheat in the hot water supply heat exchanger 18 is returned to the lowerportion of the heating hot water section 7 b.

A temperature layer is created in the heating hot water section 7 b andthis layer has such properties that that a higher location has a highertemperature. Therefore, even if hot water after it dissipated heat inthe hot water supply heat exchanger 18 is returned to the lower portionof the heating hot water section 7 b, influence on a temperature of hotwater to be sent to the heating terminal 34 is small.

Since high temperature water in the hot water supply-hot water section 7a is used as hot water to be sent to the hot water supply heat exchanger18, and high temperature water in the heating hot water section 7 b isused as hot water to be sent to the heating terminal 34, it is possibleto suppress influence of hot water supply operation received by the hotwater to be sent to the heating terminal 34.

When the flow rate sensor 33 does not detect a flow of hot/cold water,if it is detected that a hot water temperature T1 detected by thetemperature sensor 31 is higher than a hot water supply abnormaltemperature Tj (e.g., 65° C.) or higher, it is determined that anabnormal condition is encountered, the operation of the hot water supplypump 19 is stopped, the opening degree of the flow rate adjusting valve22 is fully closed to reliably prevent high temperature water in the hotwater tank 7 from being sent to the hot water supply heat exchanger 18.This can prevent high temperature water in the hot water tank 7 frombeing used uselessly, and prevent the hot water tank 7 from drying up.The predetermined temperature Tj shown in the embodiment is one example,and the invention is not limited to the embodiment.

The heat pump hot water apparatus of the embodiment is provided with theauxiliary temperature sensor 32. This prevents high temperature waterfrom coming from the hot water supply terminal 17. Next, detection ofabnormal condition carried out by the auxiliary temperature sensor 32 atthe time of the hot water supply operation will be explained.

First, when the hot water supply operation is being carried out, atemperature of hot water supplied to the hot water supply terminal 17 inthe auxiliary temperature sensor 32 is detected, a temperature deviationbetween a temperature T1 detected by the temperature sensor 31 and atemperature T2 detected by the auxiliary temperature sensor 32 isdetected.

If it is detected that the temperature T2 is higher than the temperatureT1 by a predetermined temperature Tg (e.g., 8° C.), there is apossibility that the temperature sensor 31 is erroneously operated andhigh temperature water is supplied to the hot water supply terminal 17.Therefore, the operation of the hot water supply pump 19 is stopped andthe opening degree of the flow rate adjusting valve 22 is fully closed.As a result, high temperature water does not come out from the hot watersupply terminal 17 and safety can be secured. The predeterminedtemperature Tg shown in the embodiment is one example, and the inventionis not limited to the embodiment.

Next, control of the flow rate adjusting valve 22 at the time of the hotwater supply operation will be explained.

First, if hot/cold water is supplied from the hot water supply terminal17, the flow rate sensor 33 detects that a flow rate becomes higher thana predetermined flow rate. If the flow rate sensor 33 detects that theflow rate becomes higher than the predetermined flow rate, operation ofthe hot water supply pump 19 is started.

If predetermined time α (e.g., 8 seconds) is elapsed after the operationof the hot water supply pump 19 is started, operation of the flow rateadjusting valve 22 is started and the opening degree of the flow rateadjusting valve 22 is adjusted such that the temperature T1 detected bythe temperature sensor 31 becomes equal to the hot water supply settemperature Tk. The opening degree of the flow rate adjusting valve 22is maintained at a predetermined opening degree during the predeterminedtime α.

By delaying the time to start the operation of the flow rate adjustingvalve 22 by the predetermined time a after the operation of the hotwater supply pump 19 is started, it is possible to prevent a temperatureof hot/cold water supplied to the hot water supply terminal 17 fromhunting.

If the hot water supply operation is not carried out for a long timeafter the last time hot water supply operation is completed, the hotwater supply heat exchanger 18 is cooled. Therefore, a flow rate of hotwater sent from the hot water tank 7 to the hot water supply heatexchanger 18 is maintained constant until a temperature of the hot watersupply heat exchanger 18 is stabilized after the hot water supplyoperation is started, thereby preventing the temperature of hot watersupplied to the hot water supply terminal 17 from hunting.

Next, an opening degree of the flow rate adjusting valve 22 during thehot water supply operation will be explained. The flow rate adjustingvalve 22 during a normal hot water supply operation is controlled basedon the temperature T1 detected by the temperature sensor 31. By settingthe hot water supply set temperature Tk, the opening degree of the flowrate adjusting valve 22 is adjusted such that a temperature detected bythe temperature sensor 31 becomes equal to the hot water supply settemperature Tk.

However, if a flow rate of hot/cold water sent from the water supplysource to the hot water supply heat exchanger 18 is changed by operatingthe hot water supply terminal 17, a balance between high temperaturewater sent from the hot water tank 7 to the hot water supply heatexchanger 18 and low temperature water sent from the water supply sourceto the hot water supply heat exchanger 18 is lost, and hunting of atemperature of hot/cold water supplied to the hot water supply terminal17 occurs.

Hence, in the embodiment, the opening degree of the flow rate adjustingvalve 22 is determined in accordance with variation in the flow rate ofhot/cold water detected by the flow rate sensor 33.

First, if hot/cold water comes out from the hot water supply terminal17, the opening degree of the flow rate adjusting valve 22 is adjustedsuch that the temperature T1 detected by the temperature sensor 31becomes equal to the hot water supply set temperature Tk. Then, the hotwater supply terminal 17 is operated and if a flow rate detected by theflow rate sensor 33 is varied, a heat balance at the hot water supplyheat exchanger 18 is lost.

Hence, several seconds are required until the temperature T1 detected bythe temperature sensor 31 is varied after the flow rate of hot/coldwater supplied to the hot water supply terminal 17 is varied, and if theopening degree of the flow rate adjusting valve 22 is controlled basedon the temperature T1 detected by the temperature sensor 31, verticalhunting of the temperature of hot/cold water supplied to the hot watersupply terminal 17 occurs.

Hence, in this embodiment, a flow rate Qa before predetermined time Lais always stored, and a current flow rate Qo and the flow rate Qa beforethe predetermined time La are compared with each other. As a result ofcomparison between the flow rates, if the flow rate is increased morethan a flow rate Qd, the opening degree of the flow rate adjusting valve22 is driven to a target opening degree Pt irrespective of a value ofthe temperature T1 detected by the temperature sensor 31.

The target opening degree Pt is determined in accordance with thecurrent flow rate Qo, the flow rate Qa before the predetermined time Laand a current opening Pn of the flow rate adjusting valve 22. At thattime, a fact that the current flow rate Qo is increased greater than theflow rate Qa before the predetermined time La means that an amount ofhot/cold water to be supplied to the hot water supply terminal 17 isincreased and thus, it is necessary to further supply high temperaturewater from the hot water tank 7 to the hot water supply heat exchanger18. Therefore, the target opening degree Pt is increased more than thecurrent opening Pn.

Next, the current flow rate Qo and the flow rate Qa before thepredetermined time La are compared with each other, and if the flow rateis reduced more than the flow rate Qd, the opening degree of the flowrate adjusting valve 22 is driven to the target opening degree Ptirrespective of a value of the temperature T1 detected by thetemperature sensor 31.

The target opening degree Pt is determined in accordance with thecurrent flow rate Qo, the flow rate Qa before the predetermined time Laand the current opening Pn of the flow rate adjusting valve 22. At thattime, a fact that the current flow rate Qo is reduced larger than theflow rate Qa before the predetermined time La means that the amount ofhot/cold water to be supplied to the hot water supply terminal 17 isreduced and thus, it is necessary to reduce the high temperature waterto be supplied from the hot water tank 7 to the hot water supply heatexchanger 18. Therefore, the target opening degree Pt is closed morethan the current opening Pn.

As described above, when a flow rate of hot/cold water to be supplied tothe hot water supply terminal 17 is largely varied, the opening degreeof the flow rate adjusting valve 22 is controlled to the target openingdegree Pt irrespective of a value of the temperature T1 detected by thetemperature sensor 31. According to this, it is possible to prevent atemperature of hot/cold water to be supplied to the hot water supplyterminal 17 from hunting.

Even if the opening degree is varied from the current opening Pn to thetarget opening degree Pt, the temperature T1 detected by the temperaturesensor 31 is largely overshot in some cases. Hence, in this embodiment,when the temperature T1 detected by the temperature sensor 31 is higherthan the hot water supply set temperature Tk by a predeterminedtemperature Ty (e.g., 3° C.) or more, the opening degree of the flowrate adjusting valve 22 is reduced by a predetermined opening degree D.

This predetermined opening degree D is made different between a casewhere the current flow rate Qo detected by the flow rate sensor 33 islarge and a case where the current flow rate Qo detected by the flowrate sensor 33 is small. That is, it is determined whether the currentflow rate Qo is greater than a predetermined flow rate Qb (e.g., 5L/min), and if the current flow rate Qo is greater than thepredetermined flow rate Qb, the opening degree of the flow rateadjusting valve 22 is reduced by a predetermined opening degree Da, andif the current flow rate Qo is smaller than the predetermined flow rateQb, the opening degree of the flow rate adjusting valve 22 is furtherreduced by a predetermined opening degree Db. At that time, there is arelation that the predetermined opening degree Da is larger than thepredetermined opening degree Db (Da>Db).

A variation amount of a flow rate when the opening degree of the flowrate adjusting valve 22 is small and a variation amount of a flow ratewhen the opening degree of the flow rate adjusting valve 22 is large aredifferent from each other. For example, a point Ma of a certain openingdegree Pa which is a large flow rate is to be reduced by a flow rate Qx,it is necessary to reduce the opening degree to a point Mb which is anopening degree Pb, but if attempt is made to reduce a point Mc of anopening degree Pc which is a small flow rate by the flow rate Qx, it isonly necessary to reduce the opening degree to a point Md which is theopening degree Pd. That is, it can be found that as the flow rate isgreater, the flow rate is not reduced unless the opening degree isreduced largely. Hence, in this embodiment, the predetermined openingdegree Da is set larger than the predetermined opening degree Db(Da>Db), and as the current flow rate Qo is greater, the opening degreeis reduced largely.

Since the flow rate adjusting valve 22 has such properties that as theopening degree is smaller, the flow rate is varied largely. Hence,control is performed such that a driving speed when the opening degreeof the flow rate adjusting valve 22 is reduced by the predeterminedopening degree Da is faster than a driving speed when the opening degreeof the flow rate adjusting valve 22 is reduced by the predeterminedopening degree Db.

As described above, the variation opening of the flow rate adjustingvalve 22 is controlled in accordance with two kinds of predeterminedopening degrees Da and Db depending upon whether the current flow rateQo is greater than the predetermined flow rate Qb or not, and thedriving speed of the flow rate adjusting valve 22 is controlled in thedifferent manner when the current flow rate Qo is large and when thecurrent flow rate Qo is small. According to this, it is possible toperform control suitable for properties of the flow rate adjusting valve22, and it is possible to further shorten the overshooting time. Thepredetermined temperature Ty, the predetermined flow rate Qb, and thepredetermined opening degrees Da and Db are one example, and theinvention is not limited to the embodiment.

Next, an opening degree of the flow rate adjusting valve 22 when the hotwater supply operation is stopped will be explained. First, since theheat exchanger hot water supply heat exchanger 18 keeps heat withinpredetermined time (3 (e.g., 10 minutes) after the hot water supplyoperation, the opening degree of the flow rate adjusting valve 22 at thetime of completion of the hot water supply operation is maintained, andhot/cold water is supplied to the hot water supply terminal 17 at thesame temperature as that at the time of the last time hot water supplyoperation when hot/cold water is again supplied from the hot watersupply terminal 17.

However, after the predetermined time β after the hot water supplyoperation is completed, there is a possibility that the temperature ofthe hot water supply heat exchanger 18 is decreased or hot water in thehot water tank 7 is boiled. Therefore, there is a possibility thathunting of a temperature of hot/cold water supplied from the hot watersupply heat exchanger 18 occurs when hot/cold water is supplied from thehot water supply terminal 17 next time, and high temperature hot/coldwater is supplied to the hot water supply terminal 17.

An opening degree of the flow rate adjusting valve 22 after the hotwater supply operation is completed will be explained.

It is determined whether an opening degree of the flow rate adjustingvalve 22 when the hot water supply operation is completed after thepredetermined time β after the hot water supply operation is completedis greater than a predetermined opening degree Ka. If the opening degreeof the flow rate adjusting valve 22 is greater than the predeterminedopening degree Ka, since there is a possibility that high temperaturewater is sent to the hot water supply terminal when the hot water supplyoperation is carried out next time, the opening degree of the flow rateadjusting valve 22 is driven to the predetermined opening degree Ka.

When the opening degree of the flow rate adjusting valve 22 is driven tothe predetermined opening degree Ka, the opening degree is driven to thepredetermined opening degree Ka after the flow rate adjusting valve 22is fully closed and an original position is checked. By checking theoriginal position, it is possible to keep the flow rate adjusting valve22 with a precise opening degree, and it is possible to prevent hightemperature water from being supplied to the hot water supply terminal17 when the hot water supply operation is carried out next time.

If the opening degree of the flow rate adjusting valve 22 when the hotwater supply operation is completed is smaller than the predeterminedopening degree Ka, there is no possibility that high temperature wateris sent to the hot water supply terminal when the hot water supplyoperation is carried out next time. Therefore, the opening degree of theflow rate adjusting valve 22 at the time of completion of the hot watersupply operation is kept as it is to prepare for the next hot watersupply operation.

As described above, by adjusting the opening degree of the flow rateadjusting valve 22 when the hot water supply operation is not carriedout, it is possible to prevent high temperature water from being sent tothe hot water supply terminal 17 when the hot water supply operation iscarried out next time. The predetermined opening degree Ka is set tosuch a value that a temperature of hot/cold water to be supplied doesnot exceed a predetermined temperature irrespective of a flow rate ofhot/cold water supplied from the hot water supply terminal 17, and thepredetermined opening degree Ka can appropriately be changed inaccordance with a system of a user. The predetermined time α and thepredetermined time β are one example, and the invention is not limitedto the embodiment.

Next, a casing of the heat pump hot water apparatus of the embodimentwill be explained.

FIG. 2 is a diagram showing a schematic configuration of an essentialportion of an interior of the heater as viewed from a front surface ofthe casing of the embodiment.

A longitudinally long cylindrical tank is used as the hot water tank 7.

The hot water tank 7 is disposed on one side of the casing in its widthdirection, and the antifreeze liquid refrigerant heat exchanger 4, thecompressor 1, the water/refrigerant heat exchanger 2, the watercirculating means 9, and the antifreeze liquid circulating means 41 aredisposed on the other side of the casing 50 in its width direction. Thecompressor 1, the water circulating means 9, and the antifreeze liquidcirculating means 41 are disposed at lower locations on the other sideof the casing 50 in the width direction, and the water/refrigerant heatexchanger 2 and the antifreeze liquid refrigerant heat exchanger 4 aredisposed at the location higher than the compressor 1, water circulatingmeans 9 and the antifreeze liquid circulating means 41.

The first expansion tank 37 is disposed at a location higher than thehot water tank 7. By disposing the first expansion tank 37 at thelocation higher than the hot water tank 7, it is possible to increase anamount of water which can be accommodated in the first expansion tank 37with respect to an amount of water in the hot water tank circuit. It ispreferable that the first expansion tank 37 is disposed in a space abovethe hot water tank 7. The first expansion tank 37 is covered with a heatinsulator 38. Since high temperature water is introduced into the firstexpansion tank 37, heat efficiency can be enhanced by reducing influenceof air flow caused and preventing heat radiation by the heat insulator.

The second expansion tank 44 is disposed at a location higher than theantifreeze liquid refrigerant heat exchanger 4. By disposing the secondexpansion tank 44 at the location higher than the antifreeze liquidrefrigerant heat exchanger 4, it is possible to increase an adaptableantifreeze liquid amount in the second expansion tank 44 with respect toan antifreeze liquid amount in an antifreeze liquid circuit. It ispreferable that the second expansion tank 44 is disposed in a spaceabove the water/refrigerant heat exchanger 2 and the antifreeze liquidrefrigerant heat exchanger 4. The second expansion tank 44 is coveredwith a heat insulator. Heat efficiency can be enhanced by preventingheat radiation of the second expansion tank 44 by the heat insulator.

In this embodiment, by driving the water circulating means 9, water inthe hot water tank 7 is introduced directly into the water/refrigerantheat exchanger 2, hot water produced by the water/refrigerant heatexchanger 2 is returned to the hot water tank 7, thereby heatinghot/cold water in the hot water tank 7, hot/cold water in the hot watertank 7 is introduced directly into the heating terminal 34 by drivingthe heating pump 35, hot water which dissipated heat at the heatingterminal 34 is returned into the hot water tank 7. Alternatively, hotwater produced by the water/refrigerant heat exchanger 2 may beintroduced directly into the heating terminal 34, or water in the hotwater tank 7 may be heated by hot water produced by thewater/refrigerant heat exchanger 2.

According to the embodiment, in the one casing 50, the hot water tank 7is disposed on one of sides of the casing 50, the antifreeze liquidcirculating means 41 and the heat pump circuit are disposed on the otherside of the casing 50, the water/refrigerant heat exchanger 2 isdisposed at a location higher than the compressor 1, the heavycompressor 1 which largely vibrates is disposed on a bottom plate, andthe water/refrigerant heat exchanger 2 is disposed above the compressor1. According to this configuration, stability and noise-reduction effectcan be realized when the heat pump hot water apparatus is installed, andthe casing 50 can be made smaller in size by enhancing layout balance offunctional parts in the casing 50.

INDUSTRIAL APPLICABILITY

The present invention provides a heat pump hot water apparatusespecially suitable for cold area.

1. A heat pump hot water apparatus comprising: an antifreeze liquidcircuit including antifreeze liquid circulating means which makesantifreeze liquid circulate, and an earth thermal heat exchanger whichabsorbs earth thermal by the antifreeze liquid; a heat pump circuitincluding a compressor which compresses a refrigerant and discharges thesame, a water/refrigerant heat exchanger which absorbs heat from therefrigerant discharged from the compressor to produce hot water, adecompressor which decompresses the refrigerant which dissipates heat inthe water/refrigerant heat exchanger, and an antifreeze liquidrefrigerant heat exchanger which absorbs heat from the antifreeze liquidby the refrigerant decompressed by the decompressor; and a hot watertank in which hot water heated by the water/refrigerant heat exchangeris stored; in which the antifreeze liquid circulating means, the heatpump circuit and the hot water tank are accommodated in one casing,wherein the hot water tank is disposed on one of sides of the casing,the antifreeze liquid circulating means and the heat pump circuit aredisposed on the other side of the casing, and the water/refrigerant heatexchanger is disposed at a location higher than the compressor.
 2. Theheat pump hot water apparatus according to claim 1, wherein thewater/refrigerant heat exchanger and the antifreeze liquid refrigerantheat exchanger are disposed at locations higher than the compressor andthe antifreeze liquid circulating means.
 3. The heat pump hot waterapparatus according to claim 1, further comprising a hermetic firstexpansion tank connected to the hot water tank, wherein the firstexpansion tank is disposed at a location higher than the hot water tank.4. The heat pump hot water apparatus according to claim 3, furthercomprising a hermetic second expansion tank connected to the antifreezeliquid circuit, wherein the second expansion tank is disposed at alocation higher than the antifreeze liquid refrigerant heat exchanger.5. The heat pump hot water apparatus according to claim 4, wherein thefirst expansion tank is disposed on the one side of the casing, and thesecond expansion tank is disposed on the other side of the casing.